Self-balancing centrifugal pump.



No. 808,608. PATENTED DEG. 26, 1905. E. E. K'RETZSCHMAR.

SELF BALANGING CBNTRIFUGAL PUMP..

APPLIUATION .FILED MAY 22. 1905.

3 SHEETS-SHEET OM/ b No. 808,608. PATBNTED DEG. 26, 1905.

B. E. KRBTZSGHMAR. SELF BALANCING GENTRIFUGAL PUMP.

APPLCATION PILED MAY22.1905,

3 SHEETS-SHEET 2.

E. E. KRETZSCHMAR.

SELF BALANCING CENTRIFUGAL PUMP.

APPLICATION PILEDMAY22.1905.

PATENTED DEC. 26, 1905.

HEETSSHEET 3.

UNITED STATES PATENT OFFICE.

sELF-BALANGING CENTRIFGAL PUMP.

Specification of Letters Patent.

Patented Dec. 26, 1905.

Application led May 22, 1905. Serial No. 261,700.

i residing at Alameda, in the county of Alameda and State of California, have invented certain new and useful Improvements in Self- Balancing Centrifugal Pumps, of which the following is a specification.

In centrifugal pumps with inclosed impellers there is `generated an end thrust in the direction of the shaft, the effective neutralization of which becomes a matter `of the greatest importance in seeking to attain high efficiency and to secure smooth and satisfactory running with a minimum of attendance. This end thrust is generated in both vertical and horizontal shaft types by peculiarities of construction necessitated by the inclosed form 'of impeller, and in the vertical-shaft type it is also caused by the weight of the revolving parts, such as the impeller, the shaft, and all accessories mounted upon theV shaft. The weight of `the -revolving parts Will also generate an end thrust in pumps of the horizontalshaft type when the axis of the shaft is not level. It is particularly important that such balancing of the end thrusts be attained With a minimum of loss.

The present invention therefore relates to means for automatically balancing the end thrust and holding the revolving parts in their proper relation to the stationary parts and for accomplishing these objects by hydraulic pressure. This device can be used on a pump of one or more impellers of either the horizontal or the vertical shaft type.

In the accompanying drawings, Figure 1 is a longitudinal section of a three-stage series centrifugal pump of the horizontal-shaft type. Fig. 2 is a cross-section on the line 2 2 of Fig. 1.' Fig. 3 is a cross-section on the line 3 3 of Fig. 1. Fig. 4 is a longitudinal section of a single-stage pump with the invention embodied therein. Fig. 5 is a longitudinal section of a pump of the vertical-shaft type equipped with the invention. Fig. 6 is an enlarged detail sectional view showing the manner of securing the packing-rings in place.

Referring to the drawings, it will be seen that the water enters the pump through the suction-elbow 1 and is taken up by the4 impeller 2, secured to and rotating with the shaft 3 which passes through the stuffing-boxes 4,

i packing-rings are of the same made air and Water tight by glands 5, and also passes through the ring-oiling bearings 6 with collars 7 on the outside. This shaft may be driven in any suitable manner, either by direct connection With a motor-shaft or by carrying a pulley with a bearing for a driving-belt. The impeller 2 delivers the water at its circumference to the passages between the diffusion-vanes 8, where its high speed is gradually reduced by properly designed passages and transformed into pressure. passes between the radial vanes 9 to the second impeller 10., Which again'delivers it in the same manner as before through the passages between the diffusion-vanes 11 and then between the radial vanes 12 to the third impeller 13, which in like manner delivers it through the passages between the diffusionvanes 14: into the collecting chamber 15. From the latter it is discharged through the flanged outlet 16 into the discharge pipe-line. (Not shown.)

In order to prevent the by-passing of water from the chambers 17 at the sides of the impeller back to the entrance of the impeller at 18 or to the back of the impeller at 19, there are provided packing-rings 2O 21, both of the same diameter of bore. These packing-rings do not revolve, but form running-joints with the hubs 22 of the impellers. All the impellers except the last one, 13, have passages 23 through the hub, permitting the water to enter the chamber 19 behind the same and putting this chamber under the same pressure as that at 18 in front of the impeller. As the bore for both hubs of the impeller, the pressures on both sides, due to the pressure existing in the chambers 17, theoretically balance each other, and the same holds truetheoretically of the pressures in front at 18 and at the back of the impeller at 19. In actual practice it is found that such theoretical balancing action does not always take place, partly due to inability to get exactly the same pressure on both sides of the impeller outside or inside of the diameter of the packing-rings and partly due to the impact action of the entering water on the impeller-hub at 18.

In order to balance or neutralize any re sultant end thrust in either direction, the last impeller 13 has no passages through the hub,

From the diffusion-passages the water IOO the balance-chamber 24 behind the same being tted with -a slide-valve 25, which may either rotate or not and may be of the curved surface or piston type or of the fiat plane face type. In the drawings this valve is shown as a non-rotating piston-valve loose on the shaft, the rotation with the shaft being prevented by a feather 26, which, however, permits the valve to move with the shaft endwise. It consists of a hub portion 27, which is secured between the hub 22 of the impeller 13 on one side with a collar 28 secured to the shaft on the other side, arms 29 extending from said hub portion 27, and a cylindrical valve portion 30 secured to said arms. This valve has two annular ports 31 32, the high-pressure port 31 being connected by a passage 33 and pipeline 34, controlled by a valve 35, to the outlet 16 of the collecting-chainber, while the low-pressure port 32 is connected by a passage 36 and pipe-line 37, controlled by a valve 38, to a chamber or passage of pressure lower by one or more steps than the collectingchamber or even to the suction-elbow 1, if necessitated by the condition of the case. If the water pumped is very dirty, the high-pressure pipe-line 34 may be connected to a source of clean water of pressure suitable for the purpose.

The slide-valve 25 is constructed with a negative lap in regard to both ports 31 32, so that when in its central position in regard to the same both ports are slightly open. If now the total head against which the pump is worked is 3 L, then the pressure at the end of the diffusion-passages of the first stage receiving the water from the first impeller is approximately equal to /L and the pressure at the end of the diusion-passages receiving the water from the second impeller is approximately 2 7i, while in the collecting-chamber it is 3 t. Hence if the low-pressure pipe-line 37 is connected to water-passages Linder pressure 7a and the high-pressure pipe-line 34 to a chamber under pressure 3 t and the valves 35 and 38 are open and the slide-valve 25 is in its central position, opening' both ports 31 and 32, there will be a iiow of water from the collecting-chamber 16, through the high-pressure pipe 34, passage 33and port 31 into the balance-chamber 24 and from there to the lowpressure port 32, passage 36, pipe-line 37 into the passage under pressure L. This iiow of water will result in causing a pressure in the balancingchamber 24 approximately halfway between the terminal pressures /L 'and 3 /1,-that is, about 2 /lfbut 2 t is the pressure in front of thc impeller 13, so that the.

pump is theoretically balanced. If now from any cause there is still a resultant end thrust moving the shaft 3 toward the suction-elbow 1, the valve 25 will move with it in the same direction, thereby narrowing the opening to the high-pressure port 31 and widening the opening to the low-pressure port 32, and thus allowing the influence of the low pressure to predominate, lowering the pressure in the balance-chamber 24, and therefore reducing the end thrust and bringing the shaft back to a position of balance. If the tendency of the shaft is in the opposite direction to that stated, the process is simply reversed. The valves 35 and 38 may be closed to such an extent as to reduce the by-passing of water to a minimum amount compatible with the balancing of the pump.

rI`he packing-rings 20 21 on each side of the hub of one or more impellers may be made of different diameters when necessary to balance the pump theoretically as nearly as possible when the weight of the revolving parts may require it or where it is desirable for constructive reasons.

The collars 7 outside of the ring-oiling bearings are provided to prevent undue end movement of the shaft in starting or stopping the pump.

The packing-rings may be secured in place in any desired manner and are here shown as so secured by means of screws 39, which allow slight play of said packing-rings. at right angles to the center line of shaft, the packingrings being pressed against their supports by the pressure'of the water.

In the modification shown in Fig. 4 the invention is shown as applied to a single-stage pump, the pipe 37 being in that case connected withthe inlet-elbow. In the modification shown in Fig. 5 the invention is shown as applied to a pump of the vertical-shaft type, suitable modifications being made in the arrangement and shape of the parts.

rIhe valves 41 are used forv priming the pump.

I claim- 1. A self-balancing centrifugal pump comprising a suitable casing,an endwise-movable shaft, impellers thereon, an element carried by the shaft to form an abutment, the casing having a pressure-chamber adjacent to said abutment, water connections tosaid chamber IOO IIO

from regions'of different pressures, and means l for automatically varying the proportions of water admitted to said chamber through said connections, substantially as described.

2. A self-balancing centrifugal pump comprising a suitable casing, an endwise-movable shaft, impellers thereon, an element carriedV by the shaft toform an abutment, the casing.

having a pressure-chamber adjacent to said abutment, water connections to said chamber from regions of differentpressures, and a valve controlling said connections, substantially as described.

3. -A self-balancing centrifugal pump comprising a suitable casing, an endwise-movable shaft, mpellers thereon, an element carried In Witness whereof I have hereunto set my by the shaft to form an abutment, the easing hand in the presence of tWo subscribing Wt- 10 hving a pressure-chamber adjaeenthto sd nesses. a utment, Water connections to sai o am er 5 from regions of different pressures and a valve ERNEST "EDWARD KRETZSCHMAR' controlling said connections, operated by the Witnesses: endwise movement of the shaft, substantially FRANCIS M. WRIGHT, as described. BEssIE GORFINKEL. 

